Bingowings said:

The plans of the Death Star would also be public record and there is Leia.... If Vader was kind enough to flag up her potential to go bad it would seem a shame not to explore it.

What happens to good guys when they have all the power and machinery of oppression that the former bad guy had?

I while back (before there was serious talk of a Sequel Trilogy) I was thinking about what might've happened after the war ended.

Leia never really came to terms with being the daughter of one of the biggest mass murderers in history. As a result, she doesn't understand the conflicts and temptations that Anakin and Luke faced. Ultimately the fear of losing the peace and unity that she spent her life striving for makes her vulnerable to whatever smooth-talking puppetmaster has eyes on the galaxy these days. And with weapons and resources comparable to the former Empire, there's the rising chance that history is about to repeat itself.